Inflammation is a pathological condition of an abscess caused by foreign infectious agents (bacteria, fungi, virus, various kinds of allergens, etc.). For example, when foreign bacteria invade into and proliferate in a tissue, the leukocytes of the body recognize and actively attack the proliferating foreign bacteria, during which leukocytes die and bacteria are killed by the leukocytes. The dead leukocytes and bacterial lysates accumulate in the tissue, forming an abscess.
The abscess formed by inflammation can be treated through anti-inflammation activity. Anti-inflammation activity refers to a process that reduces inflammation in which the proliferation of the foreign agent, such as bacteria, is inhibited with the aid of an anti-inflammatory agent, for example, an antibacterial agent, or in which macrophages are activated to digest and excrete the foreign materials accumulated in the abscess.
Inflammation refers to a biological protective response of tissues to harmful stimuli. Inflammation is a protective attempt by the organism to remove the injurious stimuli and to initiate the healing process for rehabilitating the cells or tissues on which organic lesion has been imposed by the invasion of the stimuli. Factors involved in these serial processes are local vascular tissues, various tissue cells of the body fluid, immune cells, etc.
Like the inflammation that is normally induced by foreign pathogens, the defense mechanism for protecting the body is indispensable for survival. However, temporally or spatially inappropriate inflammatory responses play a great role in causing a broad spectrum of diseases including those that are not believed to be related with leukocytes, such as arthritis and Alzheimer disease, as well as those apparently induced by leukocyte components, such as autoimmune diseases, asthma, and atherosclerosis.
In such inflammatory diseases, leukocytes are incited to rush to the affected tissue upon an autoimmune response where an antibody inadvertently recognizes a host protein, or by inappropriate triggers, such as accumulated tissue injury, for example, apoptotic bodies of permanent cells, extracellular cholesterol deposits, or intra-pulmonary particulates. The leukocytes, although crowded, cannot dispose of all the triggers (for example, leukocytes cannot remove or kill all autoimmune antigen-expressing host cells, or cannot phagocyte too excessively large particles from the host cells).
Hence, such diseases occasionally become chronic and continue to release inflammatory cytokines, dispatching additional leukocytes to unnecessary sites where chronic inflammation is thus formed. This inflammatory response is reported to induce chronic progressive diseases such as arteriosclerosis, obesity, insulin resistance, rheumatoid arthritis, glomerulonephritis, cancer, etc. and to play an important role in the progression of senescence.
Sepsis is a systemic inflammatory response caused by microbial infection, and may be result in severe sepsis or septic shock.
When the pathophysiology of sepsis is associated with hypoperfusion, hypotension, and organ dysfunction, it is termed as severe sepsis, which occurs in approximately 10% of all intensive care unit patients in the U.S.
Although numerous therapeutic approaches to sepsis have been advanced, the mortality rate of severe sepsis is nearly 20%. Furthermore, the annual hospital healthcare cost for patients with severe sepsis in the U.S. is the highest among all diseases and was around $20 billion.
The biggest obstacle to the discovery of therapeutics for sepsis is its diverse etiology among patients. The heterogeneous patterns of sepsis pathogenesis depend on the pathogenic organisms and sites of infection. The diverse characteristics of sepsis pathogenesis have prompted researchers to study the molecular mechanism of sepsis progression based on systemic inflammatory responses.
Various methods have been tried, for example, a method of treating sepsis using antibiotics or a method of inhibiting mediators such as TNF-α, IL-6 and IL-1, which mediate or accelerate inflammation response. However, those methods have not yet remarkably improved the survival rate of sepsis patients.
Sepsis occurs when immune responses are overactivated, including intractable inflammatory responses associated with imbalanced cytokine production. In addition, the subsequently unmanaged pro-inflammatory cytokine cascade results in whole body shock.
Furthermore, tumor necrosis factor (TNF)-α and interleukin-(IL)-1β are two major pro-inflammatory cytokines involved in sepsis and their secretion is regulated by positive feedback during systemic inflammatory responses.
When the secreted cytokines circulate in the whole body, large amounts of cytokines are produced, resulting in septic shock and secondary multiple organ dysfunctions. Therefore, therapeutic approaches to antagonize the production of these cytokines have been used for the treatment of sepsis.
For example, an anti-TNF-α antibody underwent large-scale clinical trials but was discontinued because it lacked efficacy. Literature reports suggest these failures might have been caused by two reasons.
First, because the production of TNF-α and IL-1β peaks at the early stage of systemic inflammation, it is difficult to reverse the enhanced cytokine production without inhibiting the early stage of pathogenesis.
Second, the continuous inflammatory stimuli unexpectedly restored the TNF-α level after the treatment with anti-TNF-α antibody.
On the other hand, HMGB1 (High mobility group box 1) is a constantly expressed nuclear protein, which is secreted from Gangrene cells and surrounding cells. where tissue damage occurs. There are one or more than one receptors for extracellular HMGB1. The receptor signaling induces cell division and cell migration, activates inflammation, and initiates an immune response. The cells that secrete HMGB1 include monocytes, macrophages, and human umbilical vein endothelial cells. HUVEC). Further, when HMGB1 is activated and secreted, it results in severe vascular inflammation, sepsis and death.
HMGB1 binds to RAGE (receptor for advanced glycation end products) or pattern recognition receptors (TLR2, TLR4), and then induces the expression of adhesion molecules (VCAM-1, ICAM-1, E-selectin) on endothelial cells.
An inflammatory response in an endothelial cell is initiated by HMGB1, which increases the secretion of TNF and IL-6, and induces phosphorylation of NFC-kB, ERK, and ERK-2.
It is known that HMGB1 is detected in the serum of sepsis patients and the level of HMGB1 is significantly increased in the serum of serious sepsis patients. It also is known that when the concentration of HMGB1 increases in the serum of severe sepsis patients, the possibility of the death increases. Thus, HMGB1 is the target molecule for the prevention or treatment of sepsis or other vascular inflammatory diseases.
High mobility group box protein 1 (HMGB1) has been identified as a late-stage mediator of inflammatory responses. When damaged cells undergo necrotic death, HMGB1 is released into the extracellular milieu, alerting adjacent cells to the damage. Interestingly, in immune cells such as macrophages, HMGB1 is actively secreted as a pro-inflammatory cytokine during systemic inflammatory responses.
Previous reports have indicated that secreted HMGB1 plays an important role in regulating the production of other pro-inflammatory cytokines. In this context, it has been reported that the inhibition of HMGB1 secretion successfully ameliorated the pathogenesis of sepsis in an in vivo cecal ligation and puncture (CLP) mouse model, the gold standard animal model in the field of sepsis study (Proc. Natl. Acad. Sci. U.S.A. 2004, 101, 296-301).
Briefly, the CLP mouse model is established by performing a surgical procedure to the cecum, which is the organ where the resident enteric microbiome exists. Ligating the cecum and puncturing the end with a needle causes endotoxemia by inducing polymicrobial contamination in the abdominal cavity toward the circulatory system.
This action subsequently initiates a systemic inflammatory response, namely sepsis. Regarding the role of HMGB1 in sepsis, previous researchers reported that the anti-HMGB1 antibody abrogated the lethality of the CLP-induced mouse model by inhibiting the release of HMGB1.
Furthermore, a known autophagy modulator, (−)-epigallocatechin-3-gallate (EGCG), has been studied for the prevention of lipopolysaccharide (LPS)-induced HMGB1 release by triggering the degradation of cytosolic HMGB1, thereby boosting the autophagic process.
Present inventors discovered a novel small molecule, inflachromene (ICM, Compound 1d), that inhibits the activation of BV-2 microglia-like cells, by screening drug-like compound library via Diversity-Oriented Synthesis (Korean Patent No. 10-1645942).

On the basis of our efforts on target identification using the fluorescence difference in two-dimensional gel electrophoresis (FITGE) method, the present inventors revealed HMGB1 and HMGB2 as the target proteins of ICM, and the subsequent biochemical and biophysical studies confirmed that ICM inhibits the secretion of HMGB1 and HMGB2 in microglia via the modulation of their posttranslational modifications.
The present inventors prepared various candidate compounds by changing the substituents of the above compound, ICM, and finally found the novel compounds having much more excellent anti-inflammation effect, when compared with the compound, ICM, based on the structure-activity relationship research.
The present inventors confirmed the anti-inflammation effect on the candidate compounds.
That is, the present inventors tested the anti-inflammation effect on the candidate compounds, and further searched the mechanism of inhibiting the movement and secretion of HMGB1 causing inflammation. Specifically, the present invention has been completed by testing and comparing the survival rates, etc. after administering Compound ad and the candidate compounds in CLP mouse model.
In addition, the present inventors provide novel compounds having superior therapeutic effect on sepsis, by confirming that the control of HMGB1 release is a promising strategy for treating sepsis.